Gas conduction device



March 13 1934.. W HITQHCQCK GAS CONDUCTION DEVICE Filed Sept. 23, 1930 Inventor: William J. Hitchcock,

y HIS Attorney.

Patented Mar. 13, 1934 r 1,951,150 GAS CONDUCTION DEVICE William J. Hitchcock, Scotia, General Electric Company,

New York N. Y., assignor to a corporation of Application September 23, 1930, Serial No. 483,949

4 Claims.

The present invention relates to electric discharge devices containing a gas or vapor and in particular to lamps of the positive column type wherein luminosity is produced by the conduetion of electricity through an attenuated gas.

It is the object of my invention to suppress undesired discharges between anodes in such devices, to obviate the lowering of gas pressure in such devices as a result of their operation, to suppress electrical disintegration of the anode or anodes which heretofore has been considered unavoidable, in sum, to avoid undesired discharges of electrons from electrodes at a negative potential in an ionized gas.

I have discovered that when an anode or anodes of such devices are provided with a housing having only a small aperture for the passage of current, and preferably communicating with the main discharge path only by a devious or indirect path, both the so-called clean-up or absorption of gas and the anode disintegration are reduced, alsothat the anode so housed can withstand higher negative voltages without functioning as cathode. As a consequence of my invention the critical voltage at which reverse discharges can occur is raised to a materiallyv higher value. My invention will be set forth in greater particularity in the appended claims.

The accompanying drawing shows in Fig. 1 in side elevation a lamp embodying my invention,

together with suitable current connections; Fig. 2 is an elevation partly in section on a larger scale of the anodes and anode housings, the latter being in part broken away, and Fig. 3 is a fragmental detail view of a modification.

The lamp illustrated comprises an elongated sealed envelope 1 consisting of glass, silica or other suitable transparent material. The envelope contains a suitable gas filling whereby luminosity is produced upon passage of current, such, for example, as neon, helium, argon, nitrogen or appropriate mixtures of such gases as well understood. I have employed, for example, a filling oi neon, at a pressure of about one millimeter of mercury. The lamp is provided with a thermionic cathode comprising a shell 2 and a heater 3, the latter being heated by current supplied by the conductors 4, 5 which are sealed into a stem 6. In the opposite end of the tubular envelope are located anodes, 8, 9 which preferably consist of graphite or other rough surfaced material, or which may consist of metal such as nickel or tungsten. These anodes are respectively'carried by conductors 10, 11, which are sealed through glass stems 12, 13 in the usual way.

Surrounding the anodes respectively 8 and 9 and closely spaced thereto are housings 14, 15, which, as shown in Fig. 2, are provided with restricted openings 16, 17 respectively. The housings 14, may consist of any suitable material so such as nickel, iron or non-metallic material of low vapor pressure, such as mica. The opening thereto should be of such size, ordinarily not materially in excess of ten mils diameter, that the discharge can pass through the opening to as the anode without any harmful dissipation of energy due to the development of a positive space charge but should be small enough to prevent the entry into the space surrounding the anodes within the housing of any appreciable number. of 7c metastable atoms, which are formed in the gas through which the discharge passes between the electrodes. As shown in Fig. 3, the passage of metastable atoms through the opening in the anode housing may be still further reduced by providing a baflie plate 19 in front of the opening 20 so that the discharge from the anode 21 to another electrode would have to pass through a circuitous path through the opening 20 and around the baflle plate 19. a

In the case of a lamp containing neon gas at a pressure of about 15 m. m. and being constructed as shown in Fig. 1, the length of the envelope between the juxtaposed extremities of the cathodes and anodes being about 18 inches and the inside diameter of the tubular envelope being about 1 inch, the operating voltage of such a lamp including auxiliary resistances being about 110 volts, 1 have employed in accordance with my invention housings of mil nickel sheet material and have provided in the housings an orifice, such as shown at 16, 17 of Fig. 2, of 12 mils diameter. As appearsin Figs. 2 and 3 the diameter of the orifice is materially less than the diameter of the housing. When such a lamp is operated with a current of 3.5 amperes no appreciable voltage drop occurs in the opening of the housing. At higher currents some voltage drop occurs, giving the lamp a positive characteristic similar to a f resistance. I 100 A small amount of voltage ,drop due to the. constriction of the discharge path at the opening in the housing will do no harm, but of course a substantial voltage drop will result in accompanying liberation of energy which would tend to 105 unnecessarily and perhaps harmfully heat the housing. It should be borne in mind, however, that except at very low pressures, gaseous discharge lamps have a negative'volt ampere characteristic which must be compensated for by a 1 positive resistance connected in series. The most advantageous positive volt ampere characteristic is not the linear characteristic of an ohmic resistance, such as used at 26 and 2'7, Fig. 1, but

at the particular value or I selected as the operating current of the lamp, the value of E across the ballast comprising the drop at the shield orifice and the series resistance combined being less than in the case of an ohmic resistance alone used as shown in Fig. 1..

The drawing shows for illustrative purposes an operating circuit for a gas discharge device, this circuit including the main transformer 23 as diagrammatically indicated. The anodes are connected by conductors 24, 25 across the terminals of the primary winding of this transformer. The anode circuits 24, 25 contain series resistances 26, 27. The cathode is connected to secondary winding 28 by the conductors 29, 30 whereby a low voltage current is furnished to maintain the heater 3 at an operating temperature. The shell 2 of the cathode is connected by the conductors 30, 31, 82 to a neutral point on the transformer 23 in series with an electromagnet 33. When this electromagnet is energized and its armature is drawn down a circuit is broken in a mercury switch 34 which is connected to the anode circuit 24. through a resistance 35. The breaking of the circuit in the mercury switch impresses a high inductive voltage upon a lamp and causes it to start, this operation of a mercury starting switch being well understood.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric e lamp comprising an elongated sealed envelope, a filling of a fixed gas therein at a pressure or the order of a millimeter of mercury, electrodes therein spaced apart such distance in said gas that a positive column discharge can be operated therebetween, a housing surrounding an electrode which is adapted to operate alternately as an anode and as a negatively charged inactive electrode, said housing having a single orifice of the order of ten mils diameter.

2. An electric discharge device comprising a sealed envelope, a fixed gas therein at a pressure of the order of a millimeter of mercury, a cathode, a cooperating electrode operating normally as anode, and a housing surrounding said anode, said housing being provided with an opening having a diameter materially less than the diameter of said housing.

3. A positive column lamp comprising a sealed envelope, a charge of a fixed gas therein at a pressure of the order of a millimeter of mercury, a thermionic cathode, an anode, and a housing surrounding said anode, said housing being substantially completely enclosed except for a restricted orifice.

4. An electric lamp comprising an elongated tubular envelope, a filling of a fixed gas therein at a pressure of about one millimeter of mercury, a thermionic cathode located at one end of said envelope, an anode located at the opposite end of said envelope, 2, housing closely surrounding said anode except for a restricted opening, and a baiile plate interposed between said opening and said cathode.

WHLIAM J. HITCHCOCK. 

